Comment on: Dry condition of dug wells in the dry summer season

The following features need to be considered for shallow dug wells:

1. The diameter and depth of the well;
2. The design of the well including the composition of the rings and its porosity;
3. Distance of the recharging water bodies for instance any tributaries or channels of rivers, jheel/beel or large open ponds;

4. Suitable geomorphological landforms with host shallow unconfined aquifer.

Generally water from the surrounding water bodies filled with the monsoon rainwater recharges the shallow dug wells. In other words it can be expressed, as tapping of water from the top aquifer that is believed to contain arsenic safe water.

The design used by Project Well is a modified version of the conventional wells developed by Dr. Timir Hore. The depth of such wells, in the Project Well study area, (location maps are available on the web site <projectwellusa.org>) range between 14 to 22 feet. The vital feature of such well is the pack of sand around each well, from bottom to top, that helps in recharge of water and also acts as a filter to a certain extent. The porosity of the concrete rings needs to be considered depending on the geological nature of the sediments underlying the area and which would be almost the same in Bengal and Bangladesh with some localized variation.

The shallow dug wells were constructed in several villages in the district of N-24 Parganas of West Bengal, India. In the year 2001- one; 2002 -five and in 2003 -twenty wells were excavated and in the driest month of May 2003 the column of water in each well was observed as given in the table below.